This invention relates to vertical slab gel electrophoresis systems, and in particular systems using gels of exceptional thinness and length, as needed to provide maximum resolution in the separation of nucleic acid fragments for sequencing purposes.
The difficulty of resolving nucleic acid fragments by electrophoresis has led to sequencing cell designs which are awkward to handle, susceptible to breakage and leakage, and potentially dangerous due to inadvertent mishandling. As in other electrophoretic techniques, the gels are cast and used in a sandwich-type arrangement between two flat glass plates separated by spacer strips along opposing side edges. The two plates are of unequal height, and a third plate, generally of plastic material, is placed on the outer side of the shorter glass plate with appropriate spacers along the sides and bottom to form a vertical compartment for an electrode buffer solution. The plastic plate extends above the top edge of the shorter glass plate so that the top edge of the gel slab will be immersed in the electrode buffer solution. The plastic plate and the two glass plates are clamped together along the side edges, with an intermediary greased rubber gasket along the sides and bottom of the plastic plate to prevent leakage of the buffer solution. Among the many disadvantages of such a system are the large number of pieces to be assembled, the awkwardness of obtaining proper alignment of the various plates and spacers, and the possible contamination of the buffer solution and consequently the gel itself by the grease needed to form a liquid-tight seal.
The need to overcome these problems and thereby improve the reliability of the equipment as well as provide for rapid assembly and disassembly of the parts is thus apparent. Accordingly, the present invention has been developed with these problems in mind and possibly others encountered in connection with the existing equipment.